In a network including a number of devices such as personal computers (PCs), printers, modems, etc communicating with each other through the network, a network administrator or Information Technology (IT) manager is generally in charge of managing and maintaining the network. For these purposes, the IT manager often uses computer network management tools which allow him to individually keep an inventory and monitor the devices connected to the network. Typically, one task of these tools among others is to keep a database of the PCs, such database being periodically updated by automatic transfer over the network, from each PC to the management tool, of a given set of characteristic attributes of the PC, including machine-related identifiers or parameters and network-related identifiers or parameters as will be described later.
An important factor that the IT Manager needs to take into account is that there are many situations where certain characteristic attributes of a PC may change, although the PC remains the same from the network management standpoint Below are typical examples of events that can cause such changes:                A hard disk has been reformatted;        The Internet Protocol (IP) address of a computer has been dynamically reassigned by a Dynamic Host Control Protocol (DHCP) server after a long period of inactivity (typically several days);        A motherboard has been replaced for service, requiring a new serial number to be assigned to the PC;        A new Basic Input/Output Operating System (BIOS) ROM has been plugged into the PC;        A network node name has changed;        A Local Area Network (LAN) adapter has been changed, which occurs for instance in the case of portable PCs using PCMCIA network cards.        
In such cases, at least some known network management tools might fail to correctly identify the network device after such a change. The reason is that such management tools generally consider a given PC through one single characteristic type of data (typically the serial number, IP address or computer name), so the management tool will always conclude that a PC has been replaced if said single characteristic data differs from that which was previously stored. In other words, the known management tools rely on identity between a single element of prior PC data and a freshly received single PC data to determine whether a given device is still connected to the network, or whether a new device has been connected.
For this reason, known network management tools may be subject to corruption when PC characteristic attributes are changed. Such a management tool would therefore maintain a device inventory which does not properly reflect the actual situation in the network. Therefore, the network management tasks are not properly performed and the time lost for manually correcting the inventory may be considerable.